Solar System Phenomena — Jupiter in 2018

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The chart shows the path of Jupiter across the background stars over the course of the year. Stars to magnitude +7.5 are shown. The white circles represent the planet on the first day of the month and are scaled according to apparent magnitude. The faint paths before the first circle and after the last circle represent the planet's positions in December of last year and January of next. In general, the planet moves from right to left except when it's in retrograde and proceding in the opposite direction.

The lower chart shows how the appearance of Jupiter changes over the year. Below each image is listed the date, the apparent magnitude, the apparent diameter of the disk (in arc-seconds) and the geocentric distance (in au). Note that Jupiter appears distinctly larger and brighter near the time of opposition.

Jupiter is easily the brightest object in the faint constellation Libra for much of the year. A morning sky object at the start of 2018, it has a picturesque encounter with Mars in early January. Opposition, when the planet is at its closest and brightest, occurs in May, after which is moves into the evening sky. Its position on the celestial sphere makes for more favourable viewing the farther south you are on Earth but even the northern hemisphere will get some decent observations around mid-year. The largest planet in the solar system undergoes conjunction in November, making it increasingly difficult to see from October to December, when it reappears in the east at dawn.

07 Januaryplanetary conjunction: 0.2° north of Mars
10 Februarywest quadrature
09 Marchstationary point: direct → retrograde
09 Mayopposition: magnitude −2.5, apparent diameter 44.8 arc-seconds
06 Julymaximum declination north
11 Julystationary point: retrograde → direct
06 Augusteast quadrature
19 NovemberLibraScorpius
26 Novemberconjunction
06 DecemberScorpiusOphiuchus
31 Decembermaximum declination south


The dates, times and circumstances of all planetary and lunar phenomena were calculated from the JPL DE406 solar system ephemeris using the same rigorous methods that are employed in the compilation of publications such as The Astronomical Almanac.